A discrete random variable X has probability distribution P(X = 1) = 0.15, P(X = 2) = 0.35, P(X = 3) = 0.20, and P(X = 4) = k. What is the value of k?
Answer and explanation
Correct answer: D. 0.30
- Step 1: The sum of all probabilities in a valid distribution must equal 1. Step 2. 0.15 + 0.35 + 0.20 + k = 1 => 0.70 + k = 1 => k = 0.30. Answer: 0.30. Why not the others: 0.25 leaves the sum at 0.95.
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